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Wiki Markup Never use {{return}}, {{break}}, {{continue}}, or {{throw}} statements within a {{finally}} block. When program execution enters a {{try}} block that has a {{finally}} block, the {{finally}} block always executes , regardless of whether the {{try}} block (or any associated {{catch}} blocks) executes to normal completion. Statements that cause the {{finally}} block to complete abruptly also cause the {{try}} block to complete abruptly and consequently suppress any exception thrown from the {{try}} or {{catch}} blocks. According to the _The Java Language Specification_, [§14, §14.20.2, "Execution of try-finally and try-catch-finally|http://java.sun.com/docs/books/jls/third_edition/html/statements.html#14.20.2] \[[JLS 2005|AA. References#JLS 05]\]" [JLS 2015]:

If execution of the try block completes abruptly for any other reason R, then the finally block is executed. Then there is a choice:

• If the finally block completes normally, then the try statement completes abruptly for reason R.
• If the finally block completes abruptly for reason S, then the try statement completes abruptly for reason S (and reason R is discarded).

Noncompliant Code Example

In this noncompliant code example, the finally block completes abruptly because of a return statement in the block.:

class TryFinally {
  private static boolean doLogic() {
    try {
      throw new IllegalStateException();
    } finally {
      System.out.println("logic done");
      return true;
    }
  }
}

The IllegalStateException is suppressed by the abrupt completion of the finally block caused by the return statement.

Compliant Solution

This compliant solution removes the return statement from the finally block.:

class TryFinally {
  private static boolean doLogic() {
    try {
      throw new IllegalStateException();
    } finally {
      System.out.println("logic done");
    }
    // Any return statements must go here; 
    // applicable only when exception is thrown conditionally
  }
}

Exceptions

ERRO4-J-EX0: Control flow statements whose destination is within the finally block are perfectly acceptable. For example, the following code does not violate this rule , because the break statement exits within the while loop , but not within the finally block.:

class TryFinally {
  private static boolean doLogic() {
    try {
      throw new IllegalStateException();
    } finally {
      int c;
      try {
        while ((c = input.read()) != -1) {
          if (c > 128) {
            break;
          }
        }
      } catch (IOException x) {
        // forwardForward to handler
      }
      System.out.println("logic done");
    }
    // Any return statements must go here; applicable only when exception is thrown conditionally
  }
}

Risk Assessment

Completing abruptly from Abrupt completion of a finally block masks any exceptions thrown inside the associated try and catch blocks.

Automated Detection

Related Guidelines

Bibliography

Bibliography

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